Pulse perturbations from bacterial decomposition of Chrysaora quinquecirrha (Scyphozoa: Pelagiidae)

Abstract

Bacteria decomposed damaged and moribund Chrysaora quinquecirrha Desor, 1848 releasing a pulse of carbon and nutrients. Tissue decomposed in 5-8 days, with 14 g of wet biomass exhibiting a halflife of 3 days at 22°C, which is 39 longer than previous reports. Decomposition raised mean concentrations of organic carbon and nutrients above controls by 1-2 orders of magnitude. An increase in nitrogen (16,117 lg l -1 ) occurred 24 h after increases in phosphorus (1,365 lg l -1 ) and organic carbon (25 mg l -1 ). Cocci dominated control incubations, with no significant increase in numbers. In incubations of tissue, bacilli increased exponentially after 6 h to become dominant, and cocci reproduced at a rate that was 30% slower. These results, and those from previous studies, suggested that natural assemblages may include bacteria that decompose medusae, as well as bacteria that benefit from the subsequent release of carbon and nutrients. This experiment also indicated that proteins and other nitrogenous compounds are less labile in damaged medusae than in dead or homogenized individuals. Overall, dense patches of decomposing medusae represent an important, but poorly documented, component of the trophic shunt that diverts carbon and nutrients incorporated by gelatinous zooplankton into microbial trophic webs.

Sinking of Gelatinous Zooplankton Biomass Increases Deep Carbon Transfer Efficiency Globally

“…Owing to the large size of the carcasses, most sink faster than 800 m day −1 , and we assume a global mean of 1,000 m day −1 (Lebrato, Molinero, et al, 2013). Yet the sinking rate could also be affected by the remineralization itself and carcass fragmentation (affecting remineralization rate too; Frost et al, 2012), which will make sinking speed variable. Another factor not considered in this study is that jelly-C "particles" have a wide range of sizes, from milligrams to many kilograms, thus decay rates could be higher in smaller particles, which has not been considered owing to the absence of empirical data.…”

“…While sinking through the water column, jelly‐C is partially or totally remineralized as dissolved organic/inorganic carbon and nutrients (DOC, DIC, DON, DOP, DIN, and DIP; Chelsky et al, ; Sweetman et al, ; West et al, ), and any left overs further experience microbial decomposition or are scavenged by macrofauna and megafauna once on the seabed (Sweetman et al, ; Tinta et al, ). Despite the high lability of jelly‐C (Ates, ; Sweetman et al, ), a remarkably large amount of biomass arrives at the seabed below 1,000 m. During sinking, jelly‐C biochemical composition changes via shifts in C:N:P ratios as observed in experimental studies (Frost et al, ; Sempere et al, ; Titelman et al, ). Yet realistic jelly‐C transfer estimates at the global scale remain in their infancy, preventing a quantitative assessment of the contribution to the biological carbon soft‐tissue pump.…”

“…They also can rapidly reproduce on a time scale of days and, under favorable environmental conditions, some species form dense blooms that extend for many square kilometers (Condon et al, ). These blooms have negative ecological and socioeconomic impacts by reducing commercially harvested fish species (Pauly et al, ), limiting carbon transfer to other trophic levels (Condon et al, ), enhancing microbial remineralization, and thereby driving oxygen concentrations down close to anoxic levels (Frost et al, ).…”

Jellyfish Modulate Bacterial Dynamic and Community Structure

“…Gelatinous zooplankton lack a chitinous exoskeleton, consequently their carcasses may decompose faster, compared to non - gelatinous zooplankton [7] , [9] , [10] . According to results from a few studies the rates of jellyfish – POM decomposition vary from 4–7 days for Periphylla periphylla , for Chrysaora quinquecirrha 5–8 days [13] , and up to 9 days for Catostylus mosaicus decomposing on sediments [9] . Proteins represent the most abundant fraction of jellyfish organic matter which is also reflected in their low molar C:N ratio (4.5±1.1, reviewed in 6], which further indicates that jellyfish represent high quality POM for bacteria.…”

Sinking Jelly-Carbon Unveils Potential Environmental Variability along a Continental Margin

“…During the process of jelly-biomass remineralization, dissolved organic carbon (DOC) and nutrients [14] are released, while oxygen is heavily consumed [15] . Biomass enters trophic webs consumed by bacteria or macro- and mega-fauna in benthic ecosystems [16] , [7] , [17] or through bacterioplankton while sinking [18] , [19] , [20] . Observational data of post-bloom depositions of scyphozoans and thaliaceans in continental margins [21] show that these events deliver at times more organic carbon to the seafloor than phytoplankton-based export [6] , [7] .…”